Methods and apparatus for sterility testing
Methods and apparatus for testing the sterility of a product to be administered to a patient. The sterility of the product is tested by monitoring the pH change of a culture medium in contact with any culturable organisms (e.g., bacteria) that are collected by filtration of the product to be tested.
1. A method for testing the sterility of a sample comprising:
(a) providing a filter device having a chamber and a filter configured to collect culturable organisms within the chamber;
(b) filtering a sample through the filter such that any collected culturable organisms are retained on the filter within the chamber;
(c) adding a culture medium to the chamber such that at least a portion of the collected culturable organisms are resuspended in the culture medium;
(d) after a pre-determined period of time, irradiating a fluorescent species immobilized on a substrate with excitation light emanating from a probe physically isolated from the fluorescent species immobilized on the substrate,
wherein the fluorescent species comprises a seminaphthofluorescein/human serum albumin conjugate,
wherein the fluorescent species immobilized on the substrate is in liquid communication with the culture medium,
wherein the excitation light has a wavelength sufficient to effect fluorescent emission from the fluorescent species, and
wherein the fluorescent species exhibits a first emission intensity at a first emission wavelength and a second emission intensity at a second emission wavelength, the ratio of the first and second emission intensities being dependent on pH;
(e) measuring the first and second emission intensities to determine the pH of the culture medium; and
(f) inferring from the determined pH of the culture medium the sterility of the sample.
2. The method of claim 1 , wherein the filter comprises a membrane having a pore size of about 0.45 μm.
3. The method of claim 1 , wherein the probe is physically isolated from the fluorescent species immobilized on the substrate by a window transparent to the excitation light and the fluorescent emission.
4. The method of claim 1 , wherein the probe comprises one or more optical fibers.
5. The method of claim 1 , wherein the fluorescent species is selected from the group consisting of 5′(and 6′)-carboxy -3,10-dihydroxy-spiro[7H-benzo[c]xanthene-7,1′(3′H)-isobenzofuran]-3′- one and 2-(2-chloro-3-hydroxy-9-carboxyethyl-10-oxo-10H-benzo[c]xanthen-7-yl)benzoic acid.
6. The method of claim 1 , wherein the sample comprises blood or a blood product.
7. A method for testing the sterility of a sample, comprising:
(a) providing a filter device having a chamber and a filter configured to collect culturable organisms within the chamber;
(b) filtering a sample through the filter such that any collected culturable organisms are retained on the filter within the chamber;
(c) adding a culture medium to the chamber such that at least a portion of the collected culturable organisms are resuspended in the culture medium;
(d) after a pre-determined period of time, irradiating a fluorescent species immobilized on a substrate in communication with the culture medium with excitation light having a wavelength sufficient to effect fluorescent emission from the fluorescent species,
wherein the fluorescent species exhibits a first emission intensity at a first emission wavelength and a second emission intensity at a second emission wavelength, the ratio of the first and second emission intensities being dependent on pH, and
wherein the fluorescent species comprises a 2-halo seminaphthofluorescein/albumin conjugate;
(e) measuring the first and second emission intensities to determine the pH of the culture medium; and
(f) inferring from the determined pH of the culture medium the sterility of the sample.
8. The method of claim 7 , wherein the 2-halo seminaphthofluorescein is a 2-chloro seminaphthofluorescein.
9. The method of claim 7 , wherein the 2-halo seminaphthofluorescein is 2-(2-chloro-3-hydroxy-9-carboxyethyl-10-oxo-10H-benzo[c]xanthen-7-yl)benzoic acid.
10. The method of Claim 7 , wherein the albumin is a human serum albumin.
11. The method of Claim 7 , wherein the conjugate is a 2-(2-chloro-3-hydroxy-9-carboxyethyl-10-oxo-10H-benzo[c]xanthen-7-yl) benzoic acid/human serum albumin conjugate.
12. The method of claim 7 , wherein the sample comprises blood or a blood product.